Evagination of Cells Controls Bio-Silica Formation and Maturation during Spicule Formation in Sponges

The enzymatic-silicatein mediated formation of the skeletal elements, the spicules of siliceous sponges starts intracellularly and is completed extracellularly. With Suberites domuncula we show that the axial growth of the spicules proceeds in three phases: (I) formation of an axial canal; (II) evagination of a cell process into the axial canal, and (III) assembly of the axial filament composed of silicatein. During these phases the core part of the spicule is synthesized. Silicatein and its substrate silicate are stored in silicasomes, found both inside and outside of the cellular extension within the axial canal, as well as all around the spicule. The membranes of the silicasomes are interspersed by pores of ≈2 nm that are likely associated with aquaporin channels which are implicated in the hardening of the initial bio-silica products formed by silicatein. We can summarize the sequence of events that govern spicule formation as follows: differential genetic readout (of silicatein) → fractal association of the silicateins → evagination of cells by hydro-mechanical forces into the axial canal → and finally processive bio-silica polycondensation around the axial canal. We termed this process, occurring sequentially or in parallel, bio-inorganic self-organization

Platelet-rich plasma plus bioactive glass in the treatment of intra-bony defects: a study in dogs

OBJECTIVE: This study was designed to evaluate, histomorphometrically, the association of platelet-rich plasma (PRP) and bioactive glass (BG) in the treatment of periodontal intrabony defects. MATERIAL AND METHODS: Nine mongrel dogs were included in the study. Three-wall intrabony defects were surgically created at the mesial and distal aspect of first mandibular molar and exposed to plaque accumulation for 1 month. The defects were randomly assigned to the groups: control, BG, PRP, PRP+BG. Dogs were sacrificed 90 days after the surgeries. The histometric parameters evaluated were: length of sulcular and junctional epithelium, connective tissue adaptation, new cementum, new bone, defect extension and area of new bone filling the defect. RESULTS: A superior area of new bone was observed in PRP+BG and BG (13.80±2.32 mm² and 15.63±2.64 mm², respectively) when compared to the other groups (8.19±1.46 mm² and 8.81±1.47 mm² for control and PRP, respectively). No statistically significant differences were observed in the remaining parameters. CONCLUSIONS: Within the limits of this study, it may be concluded that PRP failed to provide statistically significant improvements in the histometric parameters

Fabrication of asymmetric membranes from polyhydroxybutyrate and biphasic calcium phosphate/chitosan for guided bone regeneration

[[abstract]]Chitosan (CS) is known for its biocompatibility, antibacterial function, and wound healing acceleration, while calcium phosphate (CP) can promote bone regeneration. However, to be useful as barrier membrane for guided bone regeneration (GBR) in periodontal treatments, the membranes must have suitable mechanical strength in addition to good barrier properties. Therefore, a dense polyhydroxybutyrate (PHB) layer was integrated with a porous biphasic calcium phosphate/chitosan (BCP/CS) layer to form an asymmetric PHB-BCP/CS membrane. Moreover, for enhancing the interfacial strength, the PHB layer was chemically bonded to the BCP/CS layer through plasma-induced grafting of poly(acrylic acid) on its surface and followed by amidation with CS via carbodiimide activation. The incorporation of the PHB layer greatly increased the initial modulus and ultimate tensile strength of the membrane up to 524 and 16.5 MPa, respectively. In addition, the human gingival fibroblast (HGF) cells could proliferate very well on the PHB layer of the membrane, yet they were prohibited from down-growing through the membrane. Also, the addition of BCP particles in the CS layer increased the proliferation of osteoblast cells. Thus, the asymmetric PHB-BCP/CS membrane has the potential to be used as a barrier membrane for GBR in periodontal tissue engineering.[[incitationindex]]SCI[[booktype]]紙